I served on a Town Watch in my neighborhood years ago. We were having a hooker problem. I don't wish to be overly judgmental, but I and many of the neighbors felt the area was not an appropriate place for an open-air sex bazaar. The people I'm talking about were rather uninhibited. When Paul McCartney shouted, "Why don't we do it in the road?" they said, "Yeah, why not."
So we organized a local Town Watch under the supervision of the Philadelphia Police Department.
I was a bit surprised at how strict they were. First, we had to wear identifying clothing. Several Watch volunteers were graphic designers, and there was a competition for the logo that went on our caps. The losers were very brave, and the winner was ecstatic.
Next there was the issue of guns. The Philadelphia Police Department said we couldn't have any. They did give us these huge mag lights that we all thought might make decent billy clubs in a pinch. In the end we used them to shine light in dark places, and I saw things I wish I had not seen.
We always went in a group. I forget what our minimum number was, but we usually had four or five people.
Finally, we were told never to confront. I don't think pursuit even came up. We were supposed to call it in, and that's what we did.
So, on the basis of my experience, I would say that George Zimmerman was not acting as a legitimate Town Watch volunteer on the night he shot Trayvon Martin. Mr. Zimmerman carried a gun, he did not wear a hat with a silly logo, he acted alone, and he pursued. Very un-Town Watchly. Perhaps a better word for Mr. Zimmerman would be vigilante.